Apparatus for making plumbago crucibltg



/WM mi 2@ 'Z/ e n@ 7'.' Z/Le e I 2%. y1/b Ma Mw/WV THE HwomEPnmTmGCo. 220 Dmms ST BOSTON Unire STATES lVILLIAM SMITH, OF PITTSBURG, PENNSYLVANIA. n

fr ATENT Erica.

Specification forming part of Letters Patent N0. 40,506, dated November 3, 1863.

To all whom it may concern f Be it known that I, WILLIAM SMITH, of the city of Pittsburg, inthe county of Allegheny and State of Pennsylvania, have in vented a new and useful Improvement in Apparatus for Making Plumbago Grucibles; and I do hereby declare thc following to be a full, clear, and exact description thereof, reference being had to the accompanying drawing, forming part of this specification, which. is a perspective representation of my improved machine.

The ordinary mode of making plumbago crucibles is to draw them up and shape them by hand on a wheel, but this process is tedious and expensive, and requires the employment of expert mechanics. By my invention, however, I am enabled to make them in molds by machinery with very great rapidity and of any required shape with -the utmost exactness, and at the same time secure all the advantages of hand-made crucibles, as the plumbago is worked and drawn up in the mold by means 'of a former. which presses the plumbago against the sides of the mold.

In the drawing, c is the upright frame of my machine, and b is the bed-plate. c is a horizontal disk or wheel the shaft of which revolves in bearings in the horizontal brackets (l d', the lower one of which, d', may rest on the bed-plate b, as in the drawing. Between t-he brackets d d', and attached to the shaft of the Wheel c, is a pulley, c, which is caused to revolve rapidly by means of a belt, f, or otherwise, as may be convenient. N ear the circumference of the wheel c is a circular flange, g, which serves to hold in place centrally on the wheel the lower section of the iron mold h by means of the set-screws s. One set-screw only is vseen in the drawing, the other being diametrically opposite to it.

The mold It is made of cast-iron of any re quired shape; but if the cruciblelis designed to be of greater diameter in the middle than at top and bottom, as is usual with crucibles employed in the manufacture of steel, the

mold is parted horizontally at the point Wherev as shown in the drawing, to insure an exact flt. In the drawing the mold is shown divided perpendicularly, but this is merely done to exhibit this rabbet or lap of the sections of the mold, and to show the former l inside of it.

The mold is made open at top, of course, and it has no bottom, 'the place of which is supplied by a circular plate of metal or wood, m, which is set on the wheel e, and which tits in the mold at its lower end.

A forment, which revolves on its axis on a. vertical spindle, n, servesl to work the plumbago inside of the mold and draws it upward, at the same time giving to the inside of the crucible the shape desired. rlhis former is made of wood, and the curve of its side is that required to be given to the interior of the Crucible; butits diameterisless th an that ofthe cavity of, the crucible, so that it may be drawn up out of the mold when the crucible is finished. The length of the former l is equal to the inside height of the crucible. The spindle n, to which the former l is attached, and on which it revolves, is rigidly attached to the face-plate of the sliding bracket q,which projects horizontally 4from the upright frame a of the machine and slides up and down on slides r r on the sides of the frame.

The bracket q is in two parts, it having a sliding face-plate, t, which is attached to the projecting extremity of the bracket by a dovetailed tenon, p, Working in acorresponding mortise in the bracket, by means of which the face-plate can be moved horizontally on the bracket q. This motion is given by means of a hand-wheel, fc,- attached to a screw-shaft, u1, which works in the bracket q, the screwthreads working in a female screw cut in a tongue which projects inward from the faceplate t into a recess in the end of the bracket q. The sliding bracket q is counterpoised by two weights, zc, at the end of ropes y y, which pass over` pulleys z z at the top of the frame a, and are fastened to the bracket q.

Having thus described the construction of my apparatus for making crucibles, I will briefly explain the mode of operatin g it.

The batch from which the crucibles are made is composed of pulverized graphite or pluinbago mixed with a suitable proportion of fire-clay and formed into a dough with water in the ordinary way. A lump of this batch of sufficient quantity to form the crucible, is placedrin the bottom of the mold, the upper and lowcr sections of the mold being united andsecured to the wheel, as before described, the circular plate or false bottom m being in its place, and the bracket q being raised so as to lift the former Z entirely out of the mold before the batch isY inserted. The wheel c is then rapidly revolved, which causes the mold also to turn on its axis, which is coincident with the axis of the wheel-shaft and center of the wheel c. The sliding faceplate t of the bracket q is then set so that the axis of the shaft or spindle a is vertically over the mouth of the mold and with its axis in the same vertical line, which is done by turning the hand-wheel i: until the ends of the faceplate t are flush with the sides of the bracket q. The bracket q is then lowered, and the former l is pressed down into the plumbago batch in the bottom of the mold, the length of the former beingsuch that when the bracket q is pressed down as far as it will go the lower extremity ot' the former Z will be distant from the surface of the false bottom m of the mold the thickness which is required for vthe bottom of the crucible. The insertion of the lower end of the former l into the plumbago batch forces it up between the former and the inside ofthe mold, the batch being in a plastic condition. The handfwheel 'v is then gradually turned, which moves the face-plate t, and with it the former l, to one side, thereby pressing the batch sidewise, reducing its thickness and forcing it to rise uniformly all around the mold until it overflows at the top, if there be an excess of batch in the mold. This side motion of the former is continued until the surface of the former touches the top of the mold, which projects inward toward its center, as seen at o in the drawing, the projection 0 extending beyond the inner surface of the mold a distance equal to the thickness of the crucible at top. When the surface of the former comes in contact with the projecting rim o of the mold, the overflow of the plumhago batch is thereby cut oit' and the crucible is iinished.

lf it is desired to make the crucibles of the same thickness throughout, the curve of the face of the former lis made exactly similar to that of the inside of the mold, allowingfor the relative distance of the curves from the centers of curvature; but if the thickness of the crucible is desired to be greater at one point than another the curve of the face of the for-mer l differs accordingly from that of the inner face of the mold.

As the former revolves on its spindle a by contact with the plumbago batch, there is no rubbing on the inside of the crucible, but a smooth and regular surface is obtained, and thepressure of the batch between the former and the mold being gradually applied and opera-ting todraw up the batch between the pressing surfaces, makes the crucible without seams or faults, and is therefore greatly pret'- erable to the process of molding by direct pressure between two non-revolving surfaces.

When the crucible is formed, the former lis drawn back to the center of the mold and clevated out of it by throwing up the bracket g, the hooks i of the mold are loosened and the upper section lifted off, and, the lower section being removed from the wheel c by loosening the setscrews s, the finished crucible is raised up by means of the false bottom 1n, and is then dried and annealed in the usual way.

By my machine a crucible may be made in two or three minutes.

What I claim as my invention, and desire to secure by Letters Patent, is

Making plumbago crucibles in the manner substantially as hereinbefore described by means of a mold attached to a revolving wheel or disk and a former revolving freely on a non-revolving spindle attached to a slide-rest, susceptible of two motions, one parallel to the axis of the mold and the other at right angles thereto.

1n testimony whereof the said WILLIAM SMITH has hereunto set his hand.

WM. SMITH.

Witnesses:

W. BAKEWELL, J. (l. AT'IERBURY. 

